Impotence may be defined as the inability to develop or sustain an erection sufficient to conclude coitus. Many men are afflicted with a degree of impotence. There are psychological and physiological reasons for this inability.
The physiology of an erection involves nerve impulses which signal certain muscles to relax. These muscles, which are usually contracted, restrict arteries in the penis. When relaxed, the muscles permit a significant increase in blood flow. Three groups of erectile tissue within the penis become engorged with blood and, in turn, less flaccid. The filled tissue and the muscle structure of the penis depress adjacent veins. The flow of blood out of the penis is thus restricted which contributes to the erection. Damage to these nerves and blood vessels is a physiological reason for impotency.
Diabetes causes damage to both nerves and blood vessels. Thus diabetes often causes impotency. A significant percent of all diabetic men will suffer from impotency.
The most widely used solution for impotency involves implants which are, in essence, internal prostheses. There are two basic types of such prostheses. One type utilizes internal semi-rigid rods which can be bent up or down. The second type involves a surgically implanted pump which transfers fluid from an implanted fluid reservoir to an inflatable device in the penis.
These methods of correcting impotency have major shortcomings. The semi-rigid type does not allow the patient to control rigidity. The pump type requires hours of surgery on the penis, scrotum and abdomen and requires several days of hospitalization. Both types require surgery and are expensive. Also, once a prosthesis is implanted it makes a natural erection all but impossible.
External devices also have been used to produce and enhance an erection. Typically these devices are tourniquet-like and fit tightly around the shaft of the penis. The flow of blood from the penis through the surface veins is thereby restricted. However, because the deep dorsal vein is generally not effectively depressed, blood exiting the penis is not satisfactorily restricted. Thus the device's duration of effectiveness is relatively short. These external devices exhibit various other shortcomings including discomfort to both the user and sex partner and lack of efficacy in that the user might not achieve the desired usefulness as frequently as desired and to the extent preferred.
Drugs also can be used to induce an erection. Illustrative of this is U.S. Pat. No. 4,127,118 to Latorre which teaches the use, by injection, of a sympathomimetic amine or an adrenergic blocking agent. Latorre further states that other agents within the histamine and epinephrine groups may also be used when considered appropriate; however, while histamine is a vasodilator, epinephrine is a known vasoconstrictor. Both the chemical structure of the contemplated drugs as well as the contemplated mode of delivery distinguish the present invention from that of Latorre.
A shortcoming of Latorre is the method of delivery of the drugs. In this invasive approach, two needles are used to inject two of the three groups of erectile tissue with the drug. Thus only two of the three groups of erectile tissue respond to the treatment. This is obviously less desirable than having all three groups of erectile tissue engorged.
Being invasive, Latorre has other shortcomings. Injections are usually painful. These injections must be done in a well-lit area which is not always possible or desirable. There are health risks including hematoma, infection and scarring. If self-injection is resorted to, the drug administration is likely to be by a non-medically qualified person. As a dual needle syringe is required, there are two undesirable opportunities to hit a vein which would then dilate and allow excessive blood flow out of the penis. With two syringes there is also a greater likelihood of hitting a nerve. While Latorre teaches that his treatment can sustain an erection for 2 or 3 hours, this may be embarrassing in certain situations. In contradistinction, the present invention, because of its ease of use, overcomes the shortcomings of Latorre. All three groups of erectile tissue are engorged. There are no needles with their aforementioned shortcomings. The result is greater patient compliance. This greater compliance naturally results in the composition having a greater therapeutic value.
Birnbaum et al. U.S. Pat. No. 4,311,707 teaches the topical administration of prostaglandins or synthetic analogues of the PGE, PGA and PGF.beta. prostaglandin types to improve peripheral circulation. One alleged use is to treat impotency.
A comparison of chemical structures again differentiates the prostaglandin therapy of Birnbaum et al. and the peripheral vasodilators therapy contemplated by the present invention.
Voss et al. U.S. Pat. No. 4,801,587 describes the topical or intra-urethral administration of a vasodilator or alpha-blocker to relieve impotence by improving localized circulation. The vasodilator or alpha-blocker is combined with one or more carriers and an ointment base when administered topically. Papaverine is the vasodilator preferred in Voss et al. Dimethyl sulfoxide (DMSO) is stated to be the preferred carrier in the topically administered formulation; however, this carrier has not been approved for use by the U.S. Food and Drug Administration. Moreover, DMSO also has the undesirable effect of enhancing the systemic absorption of the vasodilator.
The problem with topically administered drugs is their limited penetration of the drug through the skin. Skin is a natural barrier and resists penetration of topically administered drugs. Without the presence of an enhancer in the topical drug compositions of Birnbaum et al. and Voss et al., only a small portion of the drug in the composition actually penetrates the skin.
The present invention provides a male impotence treatment which avoids the shortcomings of the prior art and enhances the maintenance of penis erection.